A deadly fish virus has been detected in Washington state waters for the first time, forcing a fish farm to kill its entire stock of Atlantic salmon.

Tests this month confirmed the presence of an influenzalike virus called infectious hematopoietic necrosis at a salmon farm off Bainbridge Island, the Kitsap Sun newspaper reported.

The virus, or IHN virus, does not affect humans. It occurs naturally in wild sockeye salmon and can be carried by other fish, such as herring, which sometimes pass through fishnet pens.

John Kerwin, fish-health supervisor for the Washington Department of Fish and Wildlife, said the virus is a big concern.

"Any first time it occurs, you don't fully understand the impact to wild fish," Kerwin told the newspaper. "We know it can impact (farm) fish. If we move fast, we can try to minimize the amplification."

Seattle-based American Gold Seafoods plans to remove more than a million pounds of Atlantic salmon from infected net pens in Rich Passage. In April, the company noticed fish were dying off at a fast rate. Test results this month confirmed the virus.

American Gold Seafoods, affiliated with Icicle Seafoods of Seattle, operates two hatcheries near Rochester, Thurston County, and has 120 pens off Bainbridge Island, Port Angeles, Cypress Island and Hope Island in Puget Sound.

"It's a very, very big loss for us," Alan Cook, Icicle's vice president of aquaculture, told the Kitsap Sun. "We'll clean up and start again."

Nets from 2 acres' worth of pens will be removed and disinfected. The fish farm could be running again in four months.